Myrtle

I thought they were supposed to be quite tender plants so it might be weather which is the issue. I've got a mature one in London (10ft tall until I cut it back) by a west-facing house wall so it probably benefits from a bit of heat loss from the house as well as afternoon sun and shelter. Even so all of last year's new leaves went completely crispy after getting snowed on and it's only just starting to recover with new growth, but slowly. I don't know the soil ph here but there's a camellia growing nearby with healthy looking leaves so it might be fairly acid.

If you buy a simple soil-testing kit from yr garden centre you can find out what your soil is like. Everyone says they are easy to use. After that, maybe do some research and see what you can add over time to the soil to make your next myrtle plant happier? Eg I believe coffee grounds or tea increase acidity.
My mother-in-law lives in Surrey and her soil is definitely acid, but I can't speak for the whole county obviously. She is near Guildford, and there are lots of bilberries and rhododendrons growing wild etc, so that speaks for acidic soil.
Is it possible that being in a pot made it more susceptible to frost damage this last winter and it needs a more sheltered position - did your pot have raised feet?

I kept my potted
Myrtle in a polythene tunnel over Winter but it still got terribly frost bitten. I expect there are various sources from which the Myrtles are obtained. Imported from say Italy would probably be more tender than one raised from an established bush growing in your area..

Thanks to all of you for your help. Think from the evidence that my soil is alkaline, and will have another try. But getting the myrtle plants up here is difficult, so will have to persist. Where there's a will there's a way!

Me again; where have the last two years gone! After losing so many myrtles, I thought I would have one last go. As I have managed to keep my bay and olive trees thriving so well over the years, and bring them inside to a naturally lit indoor passage during the frosts, I thought I would try the same treatment with my newly arrived Myrtle Communis. That means I have to keep it in a pot, so thought I would keep it in a plastic pot inside a massive terracotta one, which would be too heavy to move; bringing the plant inside only in its plastic pot before the frosts. The growing instructions from Crocus aren't that helpful, and don't say whether the soil should be acid or alkali, but I will leave it in the soil in arrived in for the moment, and the Telegraph growing notes recommend adding tomato feed before the winter.